Typical MEMS devices are comprised of mechanical structures built on one or more layers separated from each other and the substrate by sacrificial material. At the end of a formation process, the sacrificial material is removed thereby releasing the structure to move as intended. By their nature, these tiny structures are quite delicate and therein lies a conflict. Typical singulation or dicing techniques use water jets for cooling the substrate and dicing blade. These water jets can destroy a released MEMS device. Dicing the wafer prior to release is possible since the sacrificial material, which is still in place, serves to stiffen the microstructure against the water jets. However the task of releasing the large number of individual die cut from a wafer is also a problem. Methods to handle individual die have been proposed but in general are unsatisfactory because of the excessive handling required. Dicing after release requires protecting the delicate structures.
Several methods are proposed in the art that provide post release dicing, and each of these methods have several things in common. Firstly, they require a film to be prepared with a pattern that matches the particular device pattern on a wafer. Secondly, this film must be precision aligned and attached to the wafer. Finally, after dicing, this film must be removed. In some cases this means by mechanically peeling it off each die individually. All of these methods require special equipment and take considerable time and are expensive to accomplish.
Accordingly, an efficient method of singulation or dicing of a wafer of released die is needed.